Tubular phototube



H. M. BIELE TUBULAR PHOTOTUBE Nov. 19, 1940.

Filed July 14, 1959 INVENTOR.

N1 no APHIWHIHHIHIHMIIIIM n 5 J //w 4 v H HII H PIIIIIILIPIIIJW llllll 8 l -I\\ 9 l/ l 9 7 f.

Patented Nov. i9, 194i) PATENT GFFICE 2,222,395 ssamm rnoro'runs Harry M. Biele, Hollis, N. Y., assigner to The Associated Fress, New York, N. Y., a corporation of New York implication July lli, 1939, Serial No. 284,474

l Claim.

This invention relates to a tubular photoelectric tube which may be used to measure the transparency of fluids and the like and for scanning purposes in telephoto, facsimile, and similar transmissions.

The many objects of this invention will be apparent from the following detailed description of the invention when taken in connection with the attached drawing.

rlhis invention resides substantially in the combination, construction, arrangement and relative location of parts, all in accordance with this disclosure.

in the accompanying drawing,

Figure 1 is a side elevational view of one embodiment of a tubular phototube in accordance with this invention;

Figure 2 is a right hand end elevational view thereof;

Figure 3 is a cross-sectional View taken on the line 3 3 of Figure l; and

Figure Il is a diagrammatic view illustrating one combination employing the phototube of this invention.

ln the electrical transmission of pictures and the like, in the measurement of the transparency of fluids and the like, and for many other uses, the usual types oi photoelectric tubes may not be used to their full efficiency by reason of the constructions employed which cause a loss of a considerable proportion of the useful light operating the phototube. In an effort to minimize these diiiiculties it has heretofore been the practice in some cases to employ various types of light reecting systems in order to minimize the loss of useful light. However, even these attempts do not result in a maximum efciency in this respect because, as is well known, a considerable portion of light impinging on a mirror is absorbed and lost to useful purposes. In accordance with this invention the photoelectric tube is so constructed that a minimum amount of transmitted light is lost by scattering, absorption, and the like.

To accomplish this object, the phototube herein disclosed is made in tubular form, as clearly illustrated in Figures 1 to 3, inclusive. The phototube is provided with a base l constructed of any suitable material, such as a molded plastic, which has a central passage 2 therethrough. Mounted in and secured in this base in accordance with well known practice is a glass envelope 3, which is shown as having a generally cylindrical exterior form. It will, of course, be apparent from the following description that the invention is not limited to a strictly cylindrical form. The vessel (Cl. Z50-165) 3 is so constructed that it is provided also With an inner Wall which is composed of tWo portions united together and with the outer wall to form a sealed envelope of annular form. The inner wall comprises a cylindrical portion 5 extending at the end opposite to the base into a generally conical portion 4, which, of course, is united with the outer cylindrical wall. Atr 6 is shown the point where the tubulation tube was previously attached during the exhaust of the envelope in accordance with the usual practice in the manufacture of photoelectric tubes.

Mounted within the envelope is acylindrical cathode 'l of the type commonly used in the different forms of photoelectric tubes, which, as is clear from Figure 3, surrounds the inner portion of the envelope and lies close to the inner face of the outer wall 3. This cathode may be secured in place in the envelope in accordance with any one of a number of Well known constructional methods now commonly employed for such purposes. A lead 8 is connected at one end to the cathode, passes exteriorly ofthe vessel, and is connected to a contact 9 on the base. Surrounding the inner cylindrical portion 5 of the vessel, which it may be here noted, as will be apparent from this disclosure, need not be strictly cylin' drical, is the anode l l in the form of a ring which is Secured to a supporting rod I3 in any suitable manner, as by welding. A similar ring I2 surrounds the tubular portion 5 near the other end and the two together, in addition to acting as the anode, serve to support the anode structure in place.

Additional supporting arrangements, as are well known, may be used as desired. The ring l2 is also connected to the support I3 as by welding and a lead Id is connected at one end to the support i3, passes through the envelope, and is connected to the contact l5 on the base. It may be here noted that in place of the simple contacts 9 and l5 as shown other forms of connection may be used, including the Well known prong structures used on phototubes, by means of which they are mounted in a suitable socket and connections are made at the same time.

The combination of Figure 4 shows one assembly by means of which the phototube of this invention may be used. A suitable light source, preferably one as near a spot source as possible, is indicated at 20, the light from which shines through a condenser lens I9 onto a diaphragm, light valve, or any other suitable mechanism, depending upon the use to which the apparatus is put. In the case of picture transmission, a light valve would be used at the point I8. From there the light goes into a lens mounting I1,

which is diagrammatically illustrated as adjust-r able, so that the light projected therefrom through the tubular phototube can be concentrated to a very fine point, as is commonly necessary for such uses. The lens system should be of a type tohave a relatively long focal length so that the lens system and phototube may be separated as indicated in Figure 4. In addition, by this arrangement using a lens of long focal length, a very sharp conical beam of light may be projected through the bore of the phototube and onto the surface of a picture to be transmitted, for example, which would be wrapped upon the drum 2l. This drum is arranged to rotate in accordance with knowledge in that art so that the pin-point of light will gradually traverse the entire surfacethereof in, for example, a helical path. The light after striking the picture surface is reflected therefrom in all directions. Byl reason of the conical end 4 of the phototube most of this reflected light passes therethrough and strikes the cylindrical cathode 1 on its inner surface- By the conical construction 4 of the end of the phototube most of the light reflected to it is transmitted therethrough and not again reected away so as to be wasted. Such of therays as are reected will be transmitted to and through the diametrically opposite portions of the wall 4 so as to reach the cathode 1. Some of the more sharply reflected rays may even reach the cathode through the cylindrical wall 5. In order to increase the efficiency of reflection, that is, minimize the scattering of light, the right hand end of the phototube, instead of lying in a plane, can be arcuate,

as indicated at 22 in Figure 4, so as to have a shape complementary to the cylindrical shape` of the drum 2l and thus to be placed very close to it.

In some cases, as for example, if there are particles of dirt in the air, some of the conical beam of light transmitted through the center of the phototube may be scattered and reach the cathode I directly, which would be undesirable. In order to` guard against this, if desired the cylindrical wall 5 may be coated with any suitable opaque material, as by means of a coating I6 which when dry will form an opaque covering therefor. In this case, of course, the conical portion is left clear. Thus no light may directly reach the cathode 'I but can only reach it by reection from the surface on which the conical beam of light is focussed.

found Where the phototube is used for measuring the amount of particles in fluid, such as the amount of dust in air, for example. In this case the assembly of Figure 4 would be the same except that the drum 2I would be omitted and, of course, the coating I6 would not be used. A sample'stream of the air would be blown through the phototube with the light beam shining through it. As the light strikes the solid particles in the air, it will be scattered and impinged upon the cathode I. With the phototube connected in suitable circuits with indicating devices a direct reading of the amount of particles or dust in the air could be taken.

From the above description it will be apparent to those skilled in the art that the scope of this invention'is not limited to the physical forms and disclosure herein presented in an illustrative sense. I do not, therefore, desire to be strictly limited to the disclosure as given but rather to the scope of the claim granted me.

What I claim is:

A photoelectric tube, comprising a doublewalled vessel of annular form providing a passage therethrough, the wall of the passage comprising a cylindrical and a conical light transmitting portion, the cylindrical portion having an opaque coating thereon, and an anode and a photocathode in said vessel, the cathode receiving light through the conical portion of the vessel.

HARRY M. BIELE. 

